Divided seals, in which a sliding sealing ring has been divided into two, are used for mechanical seals in typical pumps, stirring devices, or other industrial machinery. There is a need for O-ring-type squeeze packings used in such seals to have at least one cut portion.
O-ring-type squeeze packing may be replaced after degrading due to aging; however, since an O-ring-type squeeze packing has an endless ring shape, it is necessary to disassemble a main body of a device when the packing is fitted. Therefore, there has been proposed an O-ring-type squeeze packing in which a portion in a circumferential direction is cut. However, in such an instance, problems are presented in that sealing performance is reduced in the cut portion, as well as that cut surfaces are prone to becoming displaced, therefore making it difficult to align the cut surfaces so as to be centered correctly and causing workability to become poorer.
A method for solving the above-mentioned problems involves coating the cut surfaces with an adhesive. In an instance in which this method is used, it is necessary to take care so that adhering surfaces do not become misaligned when fitted, and time is required for the adhesive to dry, which adversely effects the workability. If a misalignment of the adhering surfaces produces a step, the sealing performance will be compromised in localized areas. Also, depending on the sealed fluid, there may be instances where an adhesive cannot be used.
Another method for solving the above-mentioned problems involves using a packing 51 in which the cut portion is given a complex structure, e.g., a structure of a ball-and-socket joint 52 as shown in FIG. 6, by molding or another method (see Patent Literature 1). In an instance in which this method is used, leakage is likely to occur due to gaps dependent on the precision of the mold during fabrication, and there is also a likelihood, during mounting, of there being a variation in circumferential length, and of a gap forming in the cut portion when fitted into a groove. Also, with a packing having a complex cut portion structure, there is a limit to materials that can be used in the fabrication, and the fabrication costs are higher. Moreover, unless spares are made available in advance, remedial measures cannot be readily taken.
There has been proposed another method for resolving the above-mentioned problems in which the cut portion is given a complex shape using an incision.
A known example is an O-ring 61 in which, as shown in FIG. 7, a pair of protrusions 62, 62 and a pair of indents 63, 63 corresponding to the protrusions 62, 62 are formed on each of two end parts, wherein the protrusions 62, 62 and the indents 63, 63 engage with each other and the two end parts join each other so that misalignment does not occur at the joining part (e.g., see Patent Literature 2).
Also, there is known a ring-shaped packing 71 in which, as shown in FIG. 8 a portion in the circumferential direction is separated in a V-shape, wherein a first separated end surface 72 having a V-shaped concave surface shape and a second separated end surface 73 having a V-shaped convex surface shape join each other, thereby reproducing a ring shape that was present before separation (e.g., see Patent Literature 3).
In the examples shown in FIGS. 7 and 8, a problem is presented in that, although misalignment does not occur in the cut portion, no hooking mechanism exists in an axial direction, therefore making it difficult to temporarily hold the cut portion and dramatically reducing workability. A problem is also presented in that machining cannot be readily performed.